Attachment for screw-cutting lathes.



Patented Mar. 11, 1919.

2 SHEETS-SHEET I- E E 5 m H w a a AM 4 L. E. WOOD.

ATTACHMENT FOR SCREW CUTTING LATHES.

APPLICATION FILED JULY 20.1918.

L. E. WOOD.

ATTACHMENT FOR SCREW CUTTING LATHES.

APPLICATION FILED IULY 20,1919.

1,297,285. Patented Mar. 11,1919.

2 SHEETS-SHEET 2.

UNITED sTATEs PATENT OFFICE.

LOUIS E. woon', or FARRELL, PENNSYLVANIA.

AT ACHMENT FOR SCREW-CUTTING LATHES.

Specification of Letters Patent. Patented Mar. 11, 1919.

Application filed m 20, 1918 Serial No. 245,892. I

To all whom it may concern Be it known that I, LoUIs E. 001), a citizen of the United States, residing 'at Farrell, in the county of Mercer and State of Pennsylvania, have invented certain new and useful Improvements in Attachmentsfor Screw- Cutting Lathes; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable'others skilled in the art to which it appertains to make and use the same. 1

My invention. relates to' improvements in screw cutting lathes' and more particularly to an attachment therefor, the object being to provide simple and eflicient means for permitting closing of the feed nut upon the lead screw, after each cut of 'the tool, only at the proper time, whereby the trouble and waste of time now encountered in properly starting the tool at the end of each cut, is obviated.

With the foregoing object in view,'the invention resides in the unique construction and arrangement ofparts hereinafter fully described, claimed and illustrated.

In Figure I of the accompanying drawings, the attachment is shown in top plan view applied to a lathe, a portion of the latter being in elevation and part in horizontal section.

Fig. 2 is an enlarged vertical transverse section on the plane indicated'by the line 2+2 of Fig. 1, showing a side elevation of the attachment.

Fig. 3 is: a sectional the line 3-3 of Fig. 1. v

' Figs. 4, 5 and 6 are detail vertical sections on the planes of the lines H, 55 and 66 respectively of Fig. 3.

Fig. 7 is a longitudinal section of the sleeve Which carries the diflerently notched flanges coacting with a finger'on the feed nut in controlling the closing of the latter.

view on the plane of Fig. 8 is a side elevationof the wormwheel and the hub thereof upon which the aforesaid sleeve is slidably keyed.

Fig. 9 is a side elevation of the stub shaft upon which all parts are carried.

In the drawings above briefly described, the numeral 1 designates a plug threaded into the apron 2 of the lathe carriage 3, said plug having a bore in which the reduced outer end 4 of a horizontal stub shaft 5 is secured by a nut or the like 6. The end portion 7 of the shaft 5 remote from the nut 6, is

of less diameter than the intermediate portion 8 of said shaft and the latter isof less size than the portion which abuts the inner end of the plug 1, this portion forming a head 9, as shown. For apurpose yet to appear, the outer portion of shaft 5 is provided with a longitudinal bore 10 and with longitudinal slots 11 leading from said bore to the periphery of the shaft.

' A worm wheel 12' is rotatably mounted on the inner end of shaft 5 and meshes constantly with the lead screw 13, a nut 14- or other preferred -means being provided for holding the wheel upon the shaft. A'tubular hub 15 is provided for the worm wheel 12, said hub surrounding the portion 7 of the shaft as seen clearly in Fig. 3, and by means of a key 16 carried by the hub, and ,a

key-way 17 in asleeve 18, said sleeve and hub are connected forrotation bodily. -The .sleeve 18 is slidable upon the hub 15 and upon the portion 8 of shaft 5 and carries "a plurality of differently notched annular flanges 19 whose notches 2O coact with a finger 21 in permitting closing of the feed nut 22 around the lead screw 13, only at the proper time, said finger being secured to the upper half of the nut22 by cap screws'or the like 23. The two flanges 19 are provided with different numbers of notches-20, one of said flanges preferably having one, while the lation with'the finger. 21, according to the pitch of the screw threads to be chased. In

order that this may be done and topermit both flanges to be moved out of activezrela tion with the finger 21 when the use of the attachment is not necessary, I mount a rod 24: slidably in the bore 10 and provide its inner end with a transverse pin orthe like 25 other is'formed with four, and either one or the other flange is brought into operative rereceivable in an internal annular, groove 26 formed in sleeve 18. :The outer end-of rod 24 is provided with a knob 27 and it will thus be seen that by shifting this knob invarclly or outwardly, the sleeve 18 may be fourth-inch circular pitch. It will thus be seen that when the lead screw revolves four times, the worm wheel will turn one-fourth of a revolution or at a ratio of sixteen revo lutions of the lead screw to one revolution of the worm wheel. The flange 19 which is provided with four notches 20 cooperates with the finger 21 for chasing any whole thread such as 1, 3, 5, etc., and when the rod 24 is shifted to its central position, the flange in question comes in line with the finger 21. With the-parts in this position, an attempt to throw the feed nut into engagement with the lead screw will be resisted until one of the notches 20 comes in line with the finger, whereupon the nut will immediately close. The worm wheel and flanges then stop rotating but travel bodily with the carriage, said worm wheel then acting as a nut. As soon as the nut is thrown out of engagement with the lead screw, the carriage stops and the worm wheel and flanges 19 again start revolving. The flange with only one notch 20 is shifted into operative relation with the finger 2-1 when quarter and half threads are to be chased, and it is then possible for the feed nut to close only at one point during the revolution of the worm gear 12 which is equal to sixteen revolutions of the lead screw. It will be seen from the foregoing that the nut may be engaged with the screw only at the proper time and consequently all trouble and loss of time which has heretofore been necessary, are now obviated. Also, the necessity of using dials and the like, and the consequent trouble well known to machinists, is rendered unnecessary.

From the foregoing, taken in connection with the accompanying drawings, it will be obvious that although my invention is of extremely simple and inexpensive nature, it will be highly efficient and in every way desirable, particular emphasis being laid upon the fact that with the exception of the finger 21, the attachment is in a single unit, so that it is only necessary to tap one opening in the apron 2 of the lathe carriage, in order to install the attachment.

1 claim:

1. An attachment for screw cutting lat-hes comprising a stub shaft andmeans for rigidly mounting it on the carriage apron, a

worm wheel mounted on said shaft for mesh with the lead screw, said worm wheel hav ing a hub, a sleeve slidable on said hub and shaft and connected to the former for rotation bodily therewith, said sleeve having differently notched annular flanges, for controlling closing of the feed nut, and a rod mounted slidably in said shaft and connected to said sleeve for shifting the same to bring any flange into operative position.

2. A structure as specified in claim 1, said shaft having a longitudinal bore and a slot leading therefrom to its periphery, and said sleeve having an internal annular groove adjacent said slot, said rod being mounted slidably in sa d bore, and the connection between said sleeve and rod consisting of a pin extending from the latter through said slot and loosely received in said annular groove.

3. An attachment for screw-cutting lathes comprising a stub shaft and means at one end thereof for rigidly mounting it on the apron of a lathe carriage, the other end of said shaft being reduced in diameter, a worm gear for mesh with the lead screw of the lathe, said gear having a tubular hub rotatable on said reduced end of the shaft with its periphery flush with the periphery of said shaft, a sleeve slidable on said shaft and hub and rotatable bodily with the latter, said sleeve having a plurality of differently notched flanges for controlling the closing of the carriage feed nut, said shaft having a longitudinal slot over which one end of said sleeve slides and also having a longitudinal bore communicating with said slot, the inner side of said sleeve end being provided with a circumferential groove adjacent said slot, a. sleeve-shifting rod slidable in said bore and having a lateral projection on its inner end passing slidably through said slot and received in said groove, said rod having longitudinally spaced sockets, and a spring-pressed detent mounted in said shaft for engagement with said sockets to hold said rod in different adjustedpositions.

In testimony whereof I have hereunto set my hand.

LOUIS E. "WOOD.

Unpies of this patent may be obtained for f ve cents each, by addressing the @orcmissiener of Eatenta,

Washington, 3. 

